St Peters's was originally envisaged as the parish church for the expanding post-Famine Catholic population of Belfast. The site was provided by a wealthy Belfast flour merchant and philanthropist, Bernard Hughes[1] while the church was designed by Fr Jeremiah Ryan McAuley, who had trained as an architect before he became a priest. [2]

The church was opened on 14 October 1866. The signature twin spires were added in 1886.[3]

The decision to designate St Peter's as the diocesan cathedral was taken by Bishop Cahal Daly who celebrated the Mass on 29 June 1986 at which the building was formally named as the Cathedral Church of Down and Connor.

The exterior is of Scrabo sandstone with Scottish sandstone dressings. Internally there is a hammer-beam ceiling. [4] There were several extensive refurbishments in 1950, in 1986 under the direction of the controversial Irish artist Ray Carroll and more latterly in 2003/5 which undid much of the 1980s work